Thermoformed articles as well as methods and dies for the production thereof are known from the prior art. These articles may e.g. be food packaging or parts thereof. The packagings may contain several chambers, each being filled with a foodstuff. A mechanical weakening, e.g. in the form of a stamping or perforation, may be provided between the individual chambers, along which the chambers can be separated from each other. Such food packagings serve for subdividing larger containers into subcontainers, which can be successively consumed by a consumer. Furthermore, the chambers may be filled with different products which, after opening, are mixed or at least jointly consumed. Finally, packagings are available, in which the different contents of the compartments are to experience a different heating, which is made possible by a separation of the subcontainers.
The packagings are produced by producing the spatial structure of the articles to be produced with the corresponding number of chambers by means of thermoforming from a plane sheet material with connection areas being respectively located between them and the mechanical weakening is introduced into the respectively plane connection area between two chambers. The packagings are closed with a sealed or welded sheet which is also mechanically weakened. Here, the connection area always extends in a single plane that is in parallel to the plane of the sheet.
In food packagings in which the mechanical weakening has the plane extension described above, it is introduced into the material by means of a perforating or stamping die, while it is located in the thermoforming die. However, if the extension of the mechanical weakening deviates from the plane extension described above and extends in a plane that is inclined or vertical to it or if the extension of the mechanical weakening even extends in three direction in space, this method is not suitable for the production of such articles. Such packagings are produced in accordance with the prior art by thermoforming them first of all without a weakening and the mechanical weakening is subsequently introduced by means of a laser beam or water jet. Irrespective of the fact whether the article to be produced or the positioning of the beam or jet is moved, it is necessary to constantly readjust the focusing the beam or jet. It is only possible in this fashion to achieve equal perforation results in all areas of the weakening which is not plane.
The aforementioned method and a container produced by means of this method as a food packaging are e.g. known from WO 2005/090199 A2. This publication discloses a food packaging in the form of sterilizable containers which are connected with each other in a separable fashion. The containers are formed from a plastic material and have a flange (connection area) between each other, which is mechanically weakened and at which the containers can be separated from each other by means of breaking. The containers themselves are formed from a plastic sheet which is brought into the desired shape by means of a thermoforming process. The mechanical weakening is introduced into the flange area by means of a laser beam or a water jet after the curing of the containers. Here, it is possible by means of a corresponding positioning of the beam or jet and a corresponding focusing to introduce the weakening which extends in an uneven fashion in the direction of processing into the flange area. Although food packagings with a mechanical weakening of good quality can be produced with this method, the processing with a laser beam or water jet represents an additional process step which is connected with a quite essential expenditure and additional costs.
In view of the described prior art the object of the invention is providing a method and a die for the production of thermoformed articles such as food packagings or parts thereof, by which the articles preferably can be produced in a single processing station, wherein, cost-intensive and expensive processes such as laser beam or water jet cutting do not have to be used and by which stabilized, clampable or locking lid elements can also be produced.